1. Field of the Invention
The present invention relates to a sputtering system, and more particularly, to a method and apparatus for depositing an alloy film by sputtering such as DC magnetron sputtering of a Fe--Si--Al alloy or the like.
2. Description of the Related Art
Generally, in a highvision or high quality video tape recoder(VTR), a laminated-type head comprised of a magnetic core made of a soft magnetic material having a large saturation magnetization has been provided to ensure a high density for magnetic writing and reading operations. Also, as such a soft magnetic material, a Fe--Si--Al alloy material, which is called "sendust", has been used.
Since the saturation magnetostriction ( .lambda..sub.s) of the sendust strongly affects the efficiency of the head, it is important to set the saturation magnetostriction at an optimum value around zero, for example.
In a prior art sputtering system, since the saturation magnetostriction of the sendust is dependent upon the compositions thereof, particularly, the Si composition, the compositions of a sendust target are changed to obtain an optimum saturation magnetostriction (see: M. Takahashi et al., "Magnetic Properties of Fe--Si--Al Sputtered Films", Japan Applied Magnetics Society Trans., Vol. 11, No. 2, 1987, pp. 299-302).
In the prior art sputtering system, however, even if the compositions of a sendust target are suitably changed, the saturation magnetostriction of a deposit alloy film is changed depending on the period of use of the alloy target, which will be explained in detail later.